Set Rotation of Multiple Objects to 0 Degrees
Select via name, zero x and y euler rotations.

Test script. Finds all objects in scene with name starting with "Cube Emitter" and sets the x and y components of Euler rotation to zero.

import bpy

pattern = "Cube Emitter"
#pattern = "Cube"
scene = bpy.context.scene

cubes = [o for o in scene.objects 
        if o.name.startswith(pattern)]

for cube in cubes:
    cube.rotation_euler.x = 0
    cube.rotation_euler.y = 0